The present application relates to an overcharge/overdischarge protection integrated circuit and a battery pack using the same. In particular, the present application relates to an overcharge/overdischarge protection integrated circuit which is capable of being used for detection of an overcharge/overdischarge voltage, or detection and control of an overcharge/overdischarge voltage, and to a battery pack using the same.
At present, many electronic apparatuses which are used with a battery have mounted therein a battery pack using a chargeable secondary battery. The secondary battery is charged when the battery pack is mounted to a charger. Electronic apparatuses are also used in which, in a state where a battery pack is mounted in the electronic apparatus, an AC adapter is connected to the electronic apparatus so as to charge the secondary battery.
As described in JP-A-2003-282153, with regard to the charge/discharge control of the battery pack, typically, the voltage of the secondary battery is monitored, and when a predetermined voltage set in advance is detected, the charge or discharge control is performed. For example, a charge control FET (Field Effect Transistor) and a discharge control FET are provided in the battery pack. Then, when an integrated circuit (hereinafter, appropriately referred to as protection IC (Integrated Circuit)) detects a voltage which indicates the full charge state of the secondary battery, the charge control FET is controlled so as to stop the charge current. Similarly, when a voltage which indicates an overdischarge state is detected, the discharge control FET is controlled so as to stop the charge current. In this way, the protection IC detects the voltage of the secondary battery and controls the charge/discharge control FET so as to perform current control, so voltage detection and current control of the secondary battery in the battery pack can be performed.
A method is also known in which a voltage detector detects the voltage of the secondary battery and transmits the battery voltage to the charger or the electronic apparatus. In this case, a control circuit provided in the charger or the electronic apparatus monitors the transmitted battery voltage so as to perform charge/discharge control.